The present invention relates to a gas turbine power plant which is provided with a turbine driven by combustion gas having a high moisture content and a heat recovery system for recovering the heat of turbine exhaust gas and, more particularly, to a gas turbine power plant which comprises a compressor not employing any intercooler for compressed air, a combustor burning fuel with compressed air, a turbine driven by combustion gas of a high moisture content and a heat recovery system for recovering the heat of turbine exhaust gas, in which the moisture content of the combustion gas is increased by increasing a quantity of water or steam contained in air compressed by the compressor to be supplied into the combustor.
Conventional gas turbine power plants using humidified air are disclosed in many publications. For example, JP B 1-31012 and JP A 9-2641582 each disclose a gas turbine cycle in which air compressed by a compressor and liquid phase water used as a heat recovery medium and heated are contacted with each other in a exchanging tower, thereby to obtain humidified air or an air/steam mixture and cooled liquid phase water, and the humidified air recovers the heat of turbine exhaust gas while the cooled liquid phase water serves as a heat recovery medium to recover the heat of turbine exhaust gas and intercool the compressor, wherein the liquid phase water of a quantity corresponding to a quantity transferred to the compressed air as steam is used as a cooling medium downstream of the intercooler of the compressor cooled by the cooled liquid phase water obtained in the exchanging tower or humidification tower, and makes up the liquid phase water used in the exchanging tower and served for heat recovery.
JP B 1-19053 discloses a gas turbine system which effects heat recovery of turbine exhaust gas or the turbine exhaust gas heat recovery and intercooling of a compressor with humidified air or compressed air/water/steam mixture, obtained by injection of liquid phase water into the compressed air at a compressor outlet, without using such an exchanging tower or humidification tower as disclosed in the JP B 1-31012 and JP A 9-264158, and cools beforehand the compressed air used for forming the above-mentioned humidified air with a part of the humidified air.
Further, "J. of Eng. for Gas Turbine and Power, vol. 117, pp 499-508 (1995)" by P. Chiesa, et al. and ASME Paper 96-GT-361 "Revap Cycle: A New Evaporative Cycle Without Saturation Tower" by J. De Ruyck, et al. also disclose a gas turbine system not using a humidification tower as disclosed in JP A-1-19053.
However, the above-mentioned conventional techniques do not consider to further increase a quantity of water or steam contained in the air heated by the heat of exhaust gas from the gas turbine.
Namely, an upper limit of a water quantity that humidified air can contain, that is, a water quantity (hereunder, referred to as saturated water quantity) that saturated air contains depends on temperature, and the higher the temperature of the humidified air, the more the saturated water quantity. Therefore, even for the air humidified until it becomes a saturated condition (a relative humidity .psi., which denotes a partial pressure of steam in the humidified air to a saturated pressure of steam corresponding to temperature of the humidified air, =1) at an inlet of a heat recovery apparatus, the relative humidity becomes low by being heated in the heat recovery apparatus and having been raised in temperature. That is, for the humidified air which has been raised in temperature in the heat recovery apparatus, it is possible to further contain therein steam until it reaches a saturated condition.
Further, there are many other prior art references examples of which are as follows:
WO 98/01658 discloses a method and device for generation of mechanical work and heat in an evaporative gas turbine process in which all or part of compressed air is humidified and cooled and then led to a heat recovery apparatus, but no water is injected onto the compressed air inside the heat recovery apparatus.
EP 821136 A1 and EP 821137 A1 each disclose a system for power generation in which water cooling means is provided on a compressor or at an upstream side of the compressor to inject water into air being compressed or before compression to cool the air. In the system, a water injection device is not provided a heat recovery apparatus.
JP A 6-248974 discloses a partially regenerative type, two fluid gas turbine which is provided with a mixer for mixing compressed air and steam to humidify the compressed air, but is not provided with a water or steam injection device in a heat exchanger for heat-exchanging a turbine exhaust gas and the compressed air from the mixer.
JP A 10-103080 discloses a gas turbine cycle in which water is sprayed onto air being compressed to cool the compressed air, but the compressed air is not humidified in a recovery unit.
EP 0718472 A1 discloses a power process utilizing humidified combustion air to a gas turbine in which a saturator tower is provided to humidify compressed air and the humidified air is transferred to a heat recovery unit without any water injector and, alternatively, compressed air from a high pressure compressor is transferred to a heat recovery unit with a spray nozzle and water is injected onto the compressed air only in the heat recovery unit.
ASME Paper 95-CTP-39 "Humid Air Cycle Development Based on Energy Analysis and Composite Curve Theory" by J. De Ruyck, et al. discloses a gas turbine cycle, where heat exchange or heat recovery is effected at an intercooler, an aftercooler and a heat recovery system of high temperature exhaust gas. Compressed air from a high pressure compressor is cooled in the aftercooler by a cooling medium flowing in a conduit inside the aftercooler. The cooling medium is a part of the compressed air from the high pressure compressor, which is humidified and cooled by injection of feedwater into the conduit of the aftercooler. A part of compressed air is transferred to the heat recovery system after being supplied with feedwater and heated by the compressed water in the aftercooler. The other part of the compressed air is transferred from the aftercooler to the heat recovery system without feedwater supply before entering the heat recovery system and supplied with feedwater inside the heat recovery system.
In this system, there is room for improvement on temperature lowering of the compressed air before entering the heat recovery system.